@amitshimon,
As of now, markers can have only five possible values – “circle”, “square”, “triangle”, “cross” & “none”. However, you can position images on top of markers with the help of convertValueToPixel and convertPixelToValue methods as shown in this JSFiddle. For step-to-step tutorial on positing image over chart, please take a look at this documentation page.
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Indranil Deo
Team CanvasJS